diff --git a/usr.sbin/mtree/compare.c b/usr.sbin/mtree/compare.c
index 1732d13f766a..9008e1d90fa8 100644
--- a/usr.sbin/mtree/compare.c
+++ b/usr.sbin/mtree/compare.c
@@ -74,10 +74,7 @@ static const char *ftype(u_int);
 	}
 
 int
-compare(name, s, p)
-	char *name __unused;
-	register NODE *s;
-	register FTSENT *p;
+compare(char *name __unused, NODE *s, FTSENT *p)
 {
 	uint32_t val;
 	int fd, label;
@@ -307,8 +304,7 @@ typeerr:		LABEL;
 }
 
 const char *
-inotype(type)
-	u_int type;
+inotype(u_int type)
 {
 	switch(type & S_IFMT) {
 	case S_IFBLK:
@@ -332,8 +328,7 @@ inotype(type)
 }
 
 static const char *
-ftype(type)
-	u_int type;
+ftype(u_int type)
 {
 	switch(type) {
 	case F_BLOCK:
@@ -357,11 +352,10 @@ ftype(type)
 }
 
 char *
-rlink(name)
-	char *name;
+rlink(char *name)
 {
 	static char lbuf[MAXPATHLEN];
-	register int len;
+	int len;
 
 	if ((len = readlink(name, lbuf, sizeof(lbuf) - 1)) == -1)
 		err(1, "line %d: %s", lineno, name);
diff --git a/usr.sbin/mtree/create.c b/usr.sbin/mtree/create.c
index a42f8102c1a5..420ac5ba1721 100644
--- a/usr.sbin/mtree/create.c
+++ b/usr.sbin/mtree/create.c
@@ -85,10 +85,10 @@ static int	statd(FTS *, FTSENT *, uid_t *, gid_t *, mode_t *, u_long *);
 static void	statf(int, FTSENT *);
 
 void
-cwalk()
+cwalk(void)
 {
-	register FTS *t;
-	register FTSENT *p;
+	FTS *t;
+	FTSENT *p;
 	time_t cl;
 	char *argv[2], host[MAXHOSTNAMELEN];
 	char dot[] = ".";
@@ -145,9 +145,7 @@ cwalk()
 }
 
 static void
-statf(indent, p)
-	int indent;
-	FTSENT *p;
+statf(int indent, FTSENT *p)
 {
 	struct group *gr;
 	struct passwd *pw;
@@ -274,19 +272,13 @@ statf(indent, p)
 #define	MAXS 16
 
 static int
-statd(t, parent, puid, pgid, pmode, pflags)
-	FTS *t;
-	FTSENT *parent;
-	uid_t *puid;
-	gid_t *pgid;
-	mode_t *pmode;
-	u_long *pflags;
+statd(FTS *t, FTSENT *parent, uid_t *puid, gid_t *pgid, mode_t *pmode, u_long *pflags)
 {
-	register FTSENT *p;
-	register gid_t sgid;
-	register uid_t suid;
-	register mode_t smode;
-	register u_long sflags;
+	FTSENT *p;
+	gid_t sgid;
+	uid_t suid;
+	mode_t smode;
+	u_long sflags;
 	struct group *gr;
 	struct passwd *pw;
 	gid_t savegid = *pgid;
@@ -397,8 +389,7 @@ statd(t, parent, puid, pgid, pmode, pflags)
 }
 
 static int
-dsort(a, b)
-	const FTSENT * const *a, * const *b;
+dsort(const FTSENT * const *a, const FTSENT * const *b)
 {
 	if (S_ISDIR((*a)->fts_statp->st_mode)) {
 		if (!S_ISDIR((*b)->fts_statp->st_mode))
diff --git a/usr.sbin/mtree/misc.c b/usr.sbin/mtree/misc.c
index 1e3ca073d869..d61ffc55a979 100644
--- a/usr.sbin/mtree/misc.c
+++ b/usr.sbin/mtree/misc.c
@@ -88,9 +88,7 @@ static KEY keylist[] = {
 int keycompare(const void *, const void *);
 
 u_int
-parsekey(name, needvaluep)
-	char *name;
-	int *needvaluep;
+parsekey(char *name, int *needvaluep)
 {
 	KEY *k, tmp;
 
@@ -106,15 +104,13 @@ parsekey(name, needvaluep)
 }
 
 int
-keycompare(a, b)
-	const void *a, *b;
+keycompare(const void *a, const void *b)
 {
 	return (strcmp(((const KEY *)a)->name, ((const KEY *)b)->name));
 }
 
 char *
-flags_to_string(fflags)
-	u_long fflags;
+flags_to_string(u_long fflags)
 {
 	char *string;
 
diff --git a/usr.sbin/mtree/mtree.c b/usr.sbin/mtree/mtree.c
index 0bb40d97c72e..406da312534d 100644
--- a/usr.sbin/mtree/mtree.c
+++ b/usr.sbin/mtree/mtree.c
@@ -168,7 +168,7 @@ main(int argc, char *argv[])
 }
 
 static void
-usage()
+usage(void)
 {
 	(void)fprintf(stderr,
 "usage: mtree [-LPUcdeinqrux] [-f spec] [-K key] [-k key] [-p path] [-s seed]\n"
diff --git a/usr.sbin/mtree/spec.c b/usr.sbin/mtree/spec.c
index 69786ecd3c44..9e5f93c2dbd5 100644
--- a/usr.sbin/mtree/spec.c
+++ b/usr.sbin/mtree/spec.c
@@ -59,10 +59,10 @@ static void	 set(char *, NODE *);
 static void	 unset(char *, NODE *);
 
 NODE *
-spec()
+spec(void)
 {
-	register NODE *centry, *last;
-	register char *p;
+	NODE *centry, *last;
+	char *p;
 	NODE ginfo, *root;
 	int c_cur, c_next;
 	char buf[2048];
@@ -170,11 +170,9 @@ noparent:		errx(1, "line %d: no parent node", lineno);
 }
 
 static void
-set(t, ip)
-	char *t;
-	NODE *ip;
+set(char *t, NODE *ip)
 {
-	register int type;
+	int type;
 	char *kw, *val = NULL;
 	struct group *gr;
 	struct passwd *pw;
@@ -312,11 +310,9 @@ set(t, ip)
 }
 
 static void
-unset(t, ip)
-	char *t;
-	register NODE *ip;
+unset(char *t, NODE *ip)
 {
-	register char *p;
+	char *p;
 
 	while ((p = strtok(t, "\n\t ")))
 		ip->flags &= ~parsekey(p, NULL);
diff --git a/usr.sbin/mtree/verify.c b/usr.sbin/mtree/verify.c
index b151e595215b..40288395c39c 100644
--- a/usr.sbin/mtree/verify.c
+++ b/usr.sbin/mtree/verify.c
@@ -63,7 +63,7 @@ static void	miss(NODE *, char *);
 static int	vwalk(void);
 
 int
-verify()
+verify(void)
 {
 	int rval;
 
@@ -74,11 +74,11 @@ verify()
 }
 
 static int
-vwalk()
+vwalk(void)
 {
-	register FTS *t;
-	register FTSENT *p;
-	register NODE *ep, *level;
+	FTS *t;
+	FTSENT *p;
+	NODE *ep, *level;
 	int specdepth, rval;
 	char *argv[2];
 	char dot[] = ".";
@@ -159,12 +159,10 @@ extra:
 }
 
 static void
-miss(p, tail)
-	register NODE *p;
-	register char *tail;
+miss(NODE *p, char *tail)
 {
-	register int create;
-	register char *tp;
+	int create;
+	char *tp;
 	const char *type;
 
 	for (; p; p = p->next) {